On each wheel, a brake wheel cylinder is found above the shoes of a drum brake system. It is responsible for exerting force on the brake shoes, so they can come in contact with the drum, and thus stop the vehicle. The brake wheel cylinder has 2 pistons 1 on each side. The pistons are sealed with rubber, and have a shaft which connects the whole piston to the brake shoe.
The contact between the brake wheel cylinder and the brake shoe is accomplished when pistons are forced out through the application of pressure. The efficiency of the brake wheel cylinder is governed by the pistons. When the pistons are worn-out, the brake wheel cylinder will not be as effective in contacting the brake shoes, and thus bringing a vehicle to a halt would be difficult. Changing the pistons on a regular basis, or once worn out, is necessary to keep a good brake. Here are the steps on how to install a new brake wheel cylinder.
Step 1 - Removal of the Wheel from the Hub
Using a floor jack, lift up the vehicle until it is a little bit above the ground. Below the lower suspension control arm, slip the jack stand there to keep the wheel in place. Now, you can let down the floor jack. Take off the lugs which attach the wheel to the hub. When all the lugs are removed, take the wheel off of the hub, and set the wheel aside.
Step 2 – Removal of the Wheel Hub from the Brake Drum
With the wheels removed, you expose the retaining clips located on the outer surface of the brake drum, near the wheel studs. Remove the retaining clips using a flat-blade screwdriver. When the clips are taken off, separate the brake drum and the wheel hub. Set aside the wheel hub until you reassemble the whole thing.
Step 3 - Removal of Old Wheel Cylinder
Inside the brake drum, find the upper brake shoe spring, and take it off using pliers. Set this part aside. At the top of the backing plate, locate the old wheel cylinder, remove the wheel cylinder retaining bolts, and pull it away.
Step 4 - Installation of the New Wheel Cylinder
Place the new wheel cylinder right above the backing plate. After positioning the replacement wheel cylinder, replace the bolts that were taken off earlier and tighten them down. Attach the new cylinder to the back of the brake line, and secure it in place using a tube wrench. Replace the brake shoe spring, using pliers. Behind the new wheel cylinder, loosen its bleeder screw and push the tube of a one-man brake bleeder on the screw.
Put in the reqyired amount of brake fluid bor your particular brakes, and let it flow inside the bleeder reservoir. Once done, remove the brake bleeder and tighten the screw. Push the brake drum back on the wheel hub, then tighten the clips. Put the wheel back on, and tighten the lugs. You can now remove the jack stand and the floor jack.